Hydraulic pump jack with separable piston



Feb. 26, 1957 E. M. vANALsTYNE HYDRAULIC PUMP JACK WITH SEPARABLE PIsToN 5 Sheets-Sheet l Original Filed July `2, 1952 ,W1/Mraz :Gm 4% Kluun/vf, 5%

A Arran/x Feba 26, 1957 E. M. vANALsTYNE HYDRAULIC PUMP JACK WITH SEPARABLE PIsToN 3 Sheets-Sheet 2 Original Filed July 2, 1952 i4/@ M //VSTVA/E F/ 4 INVENToR.

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ATTORNEY Feb. 26, 1957 E. M. vANALsTYNE HYDRAULIC PUMP JACK WITH SEPARABLE PISTON 5 Sheets-Sheet 3 Original Filed July 2, 1952 AM M V/l/V/M 57m/5 I N V EN TOR.

HYDRAULIC PUMP `lACK WITH SEPARABLE PISTON Earl M. Vanalstyne, Garden Grove, Calif., assgnor of one-half to Lorin A. Lockard, Garden Grove, Calif.

Original application July 2, 1952, Seal No. 296,867, now Patent No. 2,708,912, dated May 24, 1955. Divided and this application April 21, 1955, Serial N0. 503,003

Claims. (Cl. 121-47) My invention relates to the lield of pumping equipment, and more particularly to a hydraulic pump jack, and is a division of my application Serial No. 296,867, entitled Hydraulic Pump lack, tiled July 2, 1952, and granted Patent No. 2,708,912, May 24, 1955.

In the pumping of an oil well the pump eis normally situated near the bottom o-f the hole, and is actuated by the vertical reciprocating movement of the `sucker rod which extends downwardly to the pump from the ground surface. A vertical reciprocating 4movement may be imparted to the suck-er rod by Vnumerous mechanical devices which, however, have the common disadvantage that they place a considerable mechanical stress on the sucker rod as its direction of movement is reversed. Due to the length of the sucker rod and the elasticity of the metallic material from which it is normally fabricated, the rod actually stretches .as it `reciprocat-es vertically. Thus, as the rod is moved upwardlyon one stroke it tends to be elongated, and as this process is taking place its direction is reversed and compressive forces .are exerted thereon. Obviously, under such conditions severe mechanical stresses are set up in the rod, which stresses ultimately result in progressive failure of the metal forming the rod, and the breaking or rupturing of the rod.

A major object of my invention is to provide a hyd-raulic pump jack that ceases to reciprocate the sucker rod after a break or rupture has occurred inthe rod.

Further objects are to provide a pump jack that is compact in appearance and occupies a minimum of door space, that can be fabricated from standard commercially .available materials, and which may be sold at a price that is competitive with that of existing pumping equipment of a like capacity.

These and other objects and advantages of my invention will become .apparent from the following description of two preferred forms thereof, and from the drawing illustrating these forms wherein:

rFigure 1 is a vertical cr-oss-secti-onal View of a hydraulic pump jack embodying my invention, with uid being admitted to the cylinder, and the upstroke of the piston and polished rod partially co-mpleted;

Figure 2 is a vertical cross-sectional View of said jack, with the piston at the top of the stroke;

Figure 3 is a vertical cross-sectional view of said jack, with the pist-on at the bottom of the stroke;

Figure 4 is a side elevational view of a m-odied form of hydraulic pump jack embody-ing my invention; .and

Figure 5 is a vertical cross-sectional View of a detail of construction of the jack shown in Figure 4.

yReferring now to the drawings for the general arrangement of the hydraulic pump jack embodying my invention, it will be seen that it comprises broadly a vertical elongated cylinder C shown mounted on a tripod T, the latter having its legs resting on the floor of the oil well derrick. A piston P is slidably movable within the confines of the cylinder C, and is aflixed to the upper end of a polished rod R in a conventional manner. The polished rod vR extends downwardly through the cylinder C, and

2,782,770 V..lahaine- J1 Feb. 2e, 1957 has its lower end connected to a sucker rod (not shown), with the sucker rod continuing downwardly to a conventional reciprocating pump (not shown) suitably located in the oil well from which production is to be taken.

Referring now to Figures l, 2 and 3, the cylinder C is preferably fabricated in two portions; an upper portion 10 and a lower portion 11. The upper cylinder portion 10 has a totally enclosed .dome 12 formed on the upper end thereof, with the dome 12 being offset from the longitudinal axis of the cylinder portion 10. The upper end of the cylinder portion 10 extends upwardly into the dome 12 to form a baille 13, `the purpose of ywhich will hereinafter become apparent. An annular flange 14 is shown formed on the lower end of the cylinder portion 10, and this flange engages a `complementary flange 15 lformed on the upper end of the lower cylinder portion 11. The flanges 14 and 15 are removably affixed to one another, as by bolts 14a.

The lower end of the lower cylinder portion 11 is provided with a closure 17, which closure includes a stuiling box 1S of conventional design through which the polished rod R may reciprocate. The tripod T includes a rigid member 19 which extends outwardly lfrom the closure 17, and from which -a number of legs 20 extend downwardly to the derrick door 21 or other suitable supporting surface.

Hydraulic duid may be admitted into the contines of the cylinder C by means of a supply conduit 22 which extends through the wall of the cylinder portion 11. Hydraulic iluid may be discharged from the cylinder C by means of a discharge conduit 23, which conduit is in communication with the interior of the shell portion 11, and is shown vertically .spaced above the conduit 22.

A lcylindrical valve sleeve 25 is show-n coaxially positioned Within the confines of the cylinder portion 1.1, which sleeve is formed with one or more ports 26. These ports are in horizontal alignment with :the outlet of the supply conduit 22 when the lower edge of the sleeve 25 is resting on the upper surface of the closure 17.

It will be noted in the drawing that .an annular collar 27 is shown formed on the outer surface of the 4sleeve 25, with another annular collar 2S shown formed on :the interior surface thereof; both collars preferably being in the same horizontal plane. The collars 27 and 2S each have a lower horizontal .annular surface 27a and 28a, lrespectively, the purpose of which will hereinafter be explained. The vertical surface of the collar 23 is in slidable contact with the exterior surface of a vertically positioned cylindrical guide 30 disposed within the lower contines of the cylinder portion 11, this guide having its lower end affixed to the upper surface of the closure 17. A longitudinally extending cou-nterbore 31 is shown formed in the lower part of the cylinder portion 11. This counterbore 31 defines at its upper end a body shoulder 32 with respect -to and coaxial with a longitudinally extending bore 33 of .slightly larger diameter. One or more horizontal ports 34 are shown formed in the valve sleeve 25 below the collars 27 and 28. p A number of circumferentially spaced rectangular slots 25a are shown formed .around the lower edge of the sleeve 25, .each slot providing a horizontal area 25b.

An elongated U-shaped conduit 35 extends longitudinally along one side of the cylinder C, with one leg 36 of the conduit extending through the wall of the upper cylinder portion 10 in substantially the same horizontal plane as the bottom 37 of the dome 12. The other leg 38 of the conduit 35 extends through the wall of the lower cylinder portion 11 and is in alignment with the port 32 when the sleeve 25 is in its lower position, as shown in Figures l and 3. A branch conduit 39 having a check valve 40 incorporated therein extends from the conduit 35 to pass through the wall of the cylinder por-r tion at an appreciable distance above the ange 14. A check valve 41 is shown positioned in the conduit 35 above the branch conduit 39, and a throttle or speed valve 42 is shown disposed in Ithe conduit 35 below the branch conduit 39.

A completely enclosed reservoir 44 is shown disposed adjacent the lower left side of the cylinder C. This reservoir 44 may be of relatively small capacity. An air vent pipe 45 is shown extending upwardly from this reservoir. A conduit 46 is in fluid communication with the cylinder portion 10 above the level of the conduit leg 36, which conduit extends downwardly to the reservoir 44 terminating a short distance under the top 47 thereof. A conduit 4S serves as a vent line and extends from a bore formed in the wall of the cylinder portion 11 slightly below the body shoulder 32 of the reservoir 44, extending through the top 47 of the reservoir to terminate a short distance above the bottom 49. A cylindrical hydraulic accumulator 51 may be provided, which accumulator is shown connected by a conduit 52 to the bottom 37 of the dome 12. A check valve 53 permitting downward ilow of uid is shown incorporated in the conduit 52 for reasons which will hereinafter be explained.

The piston P, for reasons that will hereinafter be explained, is preferably not formed as a single unit, but includes an annular head 55 and a cylindrical skirt 56. The head 55 has an annular flange 57 of somewhat smaller diameter extending downwardly therefrom, and forms a body shoulder 58 with the upper portion of the head 55. The skirt 56 is formed as a cylindrical shell that slidably engages the exterior surface of the flange 57. Suitable fluid sealing such as rings may be positioned on the exterior surface of the skirt in a conventional manner. The interior surface of the cylindrical shells 10 and 11 should be given a highly polished surface thereby caused to move upwardly at a velocity dependent upon the rate of flow of the hydraulic fluid entering the cylinder C through the conduit 22. As the piston P moves upwardly, the polished rod R is likewise moved upwardly, as well as the sucker rod attached to the polished i rod. Thus, the pump situated at the bottom of the well is actuated to take a pumping stroke.

The piston P continues upwardly under the influence of the hydraulic uid being admitted to the cylinder C until the piston P has assumed the position shown in Figure 2. Hydraulic lluid is then admitted into the upper end of the conduit 35 and ows downwardly therein past the check valve 41 into the annular space 61 formed between the interior surface of the counterbore 31 and the exterior surface of the cylindrical guide 30. The hydraulic fluid in the space 61 may pass through the port 34 and slots a so as to exert upward pressure :on the 'horizontal surfaces 2511, 27a and 28a. Since the area provided by the surfaces 25b, 27a `and 28a is greater than the annular horizontal surface 62 formed on the upper end of the sleeve 25, the sleeve 25 is caused to move upwardly into the position shown in Figure 2 under the influence of hydraulic iluid admitted to the space 61. As the valve sleeve 25 is moved to its upper position, the port 26 is brought into horizontal alignment with the ldischarge conduit 23.

yThe weightsupported by the sucker rod S and polished rod R causes the piston P to immediately start to descend whereby hydraulic Ailuid will be discharged through the conduit 23g-thejport 26 having been brought into Yalignment therewith. As the'piston `P starts todescend'on its .4 down stroke, upwardly directed hydraulic pressure is maintained on the sleeve, since the check valve 41 positively restrains any upward ilow of hydraulic uid in the conduit 35. The check valve 41 at all times, however, permits flow of hydraulic iluid from lthe conduit into the cylinder C. Thus, after the piston P has moved downwardly to the position shown in Figure 3, there is no longer appreciable hydraulic pressure above the piston P, and a portion of the hydraulic fluid in the conduit 35 below the check valve 41 will flow through the check valve 40 into the contines of the cylinder C. As such flow of hydraulic fluid takes place the pressure on the sleeve surfaces 25b, 27a and 28a is reduced `to substantially the pressure existing above the piston P in the cylinder C. Hence, the valve sleeve 25 will move downwardly under the inuence of the hydraulic pressure exerted on the upper horizontal end 62 -thereof to the position shown in Figure 3.

It will be apparent that should the piston P be formed in one piece, and the polished rod R or the sucker rod S aixed thereto break, that the piston could be caused to move upwardly in the cylinder C with sufficient velocity as to -do considerable damage to the upper portion thereof. Do eliminate this danger the piston P is formed of two component parts, the head 55, and the skirt 56.

In moving the piston P upwardly, Ithe hydraulic fluid exerts upward pressure on the surface of the lower annular edge of the ange 58 as well as on the bottom surface of the head 55. The combined areas of these two sur faces are considerably greater than the surface area of the lower annular edge of the skirt 56, with the result that upon the breakage of the polished rod R or the sucker rod the upward force exerted upon the head by the hydraulic uid in the cylinder C is considerably greater than the upward force exerted upon the skirt 56. This force differential permits lthe head 55 and skirt 56 to separate whereby hydraulic iluid is allowed to ilow upwardly to the top of the cylinder C and escape through the conduits 46 and 52. The head 55 will lose most of its upward velocity after it has separated from the skirt 56 and hence damage to the upper end Aof the cylinder C will be minimized or even prevented.

Referring now to Figures 4 and 5., -there is shown a modified form of pump jack embodying the present invention. In its general arrangement this embodiment is seen to comprise avertical elongated cylinder C mounted on a tripod T; the latter having its legs resting upon a base B. A piston P is slidably movable within the con fines of the cylinder C', and is aiiixed to the lupper end of a polished rod R in a conventional manner. The base B also mounts a two-stage pressure tank and a conventional centrifugal pump 72.

Referring again to Figures 4 and 5, the cylinder C is preferably fabricated in three portions; an upper portion 74, an intermediate portion 76, and a lower portion 78. The upper cylinder portion 74 includes a totally enclosed dome formed Von its upper end. The three cylinder portions may be interconnected by means of complementary sets of anges 82 and 84, which flanges may be secured together by conventional fastening means, such as bolt and nut combinations 85. The vlowerend of the lower cylinder portion 78 is provided with a stuffing box 86 of conventional design through which the polished rod R may reciprocate.

Hydraulic uid may be admitted into the cylinder C' through a supply conduit 88 which interconnects the intermediate portions 76 of the cylinder and the high pressure section 90 of the pressure tank 70. Hydraulic fluid may be discharged from the cylinder by means of a discharge conduit 92 which interconnects the intermediate portion of the cylinder with the low s-tage section 94 of the pressure tank 70. n

A cylindrical valve sleeve 96 is shown coaxially pos-1- tioned within the lower and intermediate portions of the cylinder, which sleeve cooperates with the supply and discharge conduits 88 and 92 respectively, -in a Isimilar fashion to that of the valve sleeve 25 described previously in connection with the embodiment shown in Figures 1, 2 and 3.

The other parts of the embodiment of Figures 4 and 5 are fully described in my aforementionedPatent No. 2,708,912.

The operation of this modified form of this invention is substantially similar to that described in conjunction with the embodiment shown in Figures l, 2 and 3. Thus, hydraulic liuid is conducted into the cylinder through the supply conduit 88; the valve sleeve 96 being in its lower position as shown in Figure 5. The entry of this hydraulic fluid causes the piston P to move upwardly within the cylinder, and when the piston has reached the upper limit of its stroke, hydraulic fluid will ow down the U-shaped conduit 98 and through its bottom leg 104 into the counterbore 124. This iluid exerts upward pressure on the underside of the collar 127 so as to cause the valve sleeve 96 to rise. As the valve sleeve is moved into its upper position, its port 136 is brought into horizontal alignment with the discharge conduit 92 whereby the weight supported by the polished rod R will cause the piston P' to descend. As the piston descends, the hydraulic uid disposed thereunder will be discharged through the discharge conduit 92 into the low pressure section 94 of the pressure tank 70.

It should be particularly observed that in case the polish rod or sucker rod string should break and the piston P separate, the skirt portion 56 of the latter will fall within the cylinder C until it comes to rest upon the upper end j of the valve sleeve 96. The weight of the skirt 56' will cause the valve sleeve 96 to descend to its lowered position of Figure 5. In this position the skirt 56 will cover the fluid supply conduit 88 so as to prevent additional pressurized supply fluid from entering the cylinder C.

Although l have hereinabove described what is presently believed to be the preferred apparatus embodying the present invention, it will be apparent to those skilled in the art that various changes and modifications may be made thereto Without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. A pressure relieving piston for use within a cylinder, comprising: a piston head of smaller diameter than said cylinder; a piston rod affixed thereto; and an annular skirt positioned on the under side of said head, said skirt having a sealing relationship with said cylinder and with said head and skirt being sufficiently diierent in mass and the area exposed -to a iluid exerting pressure thereon that they will move at different velocities and separate upon said piston rod breaking.

2. A pressure relieving piston for use within a cylinder, comprising: a piston head of smaller diameter than said cylinder; a piston rod aixed thereto; and an annular skirt positioned on the under side of said head, said skirt having a sealing relationship with said cylinder and with said head and skirt being held together as an integral unit when hydraulic uid is exerting pressure on the under side thereof, said head and skirt being sucently different in mass and to the area exposed to said hydraulic tluid that they will move upwardly at diterent velocities and separate upon said piston rod breaking.

3. A hydraulic pump jack that includes: a cylinder; a piston head situated within the contines of said cylinder of smaller diameter than said cylinder; a piston rod aixed to said head; and a skirt slidably movable in said cylinder and situated on the side of said piston on which hydraulic luid exerts pressure, said skirt having a sealing relationship with said cylinder and with said head and skirt being held together as an integral unit by the hydraulic pressure exerted thereon during the time the movement of said piston is controlled by said piston rod, said head and skirt being suilciently different in mass and the area exposed to said uid that they will move at different velocities and separate upon said rod breaking.

4. A hydraulic pump jack that includes: a cylinder; a. piston head situated within the contines of said cylinder and having a smaller diameter than said cylinder, with said head having an annular recess formed on the under side thereof; a piston rod aixed to said head; and an annular skirt slidably movable in said piston and being held in contact with said recess by pressure exerted by hydraulic fluid that is present on the under side of said head and skirt, said skirt having a sealing relationship with said cylinder and said head and skirt being suciently diierent in mass and the area exposed to said fiuid that they will move at different velocities and separa-te upon said rod breaking.

5. A hydraulic pump jack that includes: a vertical cylinder; a supply port formed in the lower portion of said cylinder; a hydraulically operated sleeve valve coaxially movably mounted in the lower portion of said cylinder, with said sleeve when in the lower position permitting fluid to be introduced into said cylinder through said supply port so as to cause said piston to complete an upstroke, and 'said sleeve when in the upper position permitting said uid to be discharged from said cylinder to cause said piston to complete a downstroke; a rod extending coaxially into said cylinder; a piston vertically slidably movable in said cylinder, said piston having a head of smaller diameter than said cylinder to which is alixed said rod and an annular skirt positioned on the underside of said head, said skirt having a sealing relationship with said cylinder and with said head and skirt being held together as an integral unit when hydraulic iluid is exerting pressure on the underside thereof, said head and skirt being suiciently different in mass and to the area exposed to said hydraulic fluid that they will move upwardly at dilerent velocities and separate upon said rodrbreaking whereby said skirt will fall and cause said supply port to be covered.

References Cited in the le of this patent UNITED STATES PATENTS n 2,103,963 Wineman Dec. 28, 1937 2,708,912 Vanalstyne May 24, 1955 

